Ingredient

Prawns

Prawns cook in about two minutes and are ruined in about three. They are also sold in a bewildering number of forms, and the single most useful piece of advice about them is unglamorous: buy them shell-on and raw, because the shells are worth as much as the meat and pre-cooked prawns can only be overcooked further.

Why they go rubbery, and the one visual cue

Prawn muscle is made of short protein fibres with very little connective tissue. Heat makes those proteins contract and squeeze out water, and because there is no collagen to convert into gelatine, there is no second stage where a prawn becomes tender again. It goes from raw to perfect to rubbery, in that order, quickly, and never comes back.

The useful cue is shape. A raw prawn is straight or gently curved. As it cooks it curls into a C. Keep cooking and it curls further, into a tight O.

A C is cooked. An O is overcooked. It is the most reliable visual check in cooking and it works for every size of prawn.

The other cue is colour and opacity: pink all over and no translucency left in the thickest part. Both cues arrive at roughly the same moment, and the moment is much sooner than most people expect. Take them off the heat at that point, because they carry on cooking in their own residual heat.

What to buy

Raw, shell-on

The best value and the best result. You get the shells, which are the base of a bisque, a stock or a sauce — see bisque. Peeling takes minutes.

Raw, peeled

Convenient, more expensive per unit of meat, and you have thrown away the flavour base.

Cooked, peeled

Already at the end of their cooking. Fine cold in a sandwich or a salad; in a hot dish they can only get worse. If you must use them, add them at the very end purely to warm through.

Frozen

Usually better than "fresh" at a supermarket counter, most of which was previously frozen and thawed anyway. Frozen raw shell-on prawns are the sensible default.

Sizes

Named inconsistently — prawn, king prawn, tiger prawn, jumbo — and the names describe size and species loosely. Buy by count per kilogram if the packet says.

Cold-water and warm-water

Cold-water prawns are smaller, sweeter and more delicate. Warm-water prawns are larger and meatier. Different, not better or worse.

Preparing and cooking them

1. Thaw frozen prawns in the fridge, or in a bowl of cold water if you are in a hurry. Never in warm water.
2. Pat them dry — properly dry. Wet prawns steam in the pan and will not colour.
3. Peel them if you want, keeping every shell and head in a bag in the freezer for stock. The head contains a great deal of flavour.
4. Devein the larger ones: run a knife shallowly down the back and lift out the dark thread, which is the gut. Cosmetic in small prawns, worth doing in large ones where it can taste gritty.
5. Get the pan genuinely hot, with oil or butter. A hot pan cooks them fast enough to colour the outside before the inside overcooks.
6. Cook in a single layer, without crowding, for around a minute a side.
7. Take them out as soon as they are pink and curled into a C. If they are going back into a sauce, take them out early and return them at the very end.
8. Season after cooking as well as before — prawns take salt well and a squeeze of lemon at the end lifts them.

What to do with them

• Fried hard in garlic butter with chilli and parsley, and bread to mop the pan. Nothing improves on this.
• Grilled or barbecued shell-on, which protects the meat and gives you something to suck the juices from.
• In a curry or a laksa, added in the last two minutes.
• In a stir-fry, cooked separately and returned at the end.
• Cold, in a prawn cocktail, where cooked prawns are entirely appropriate.
• Butterflied — split down the back and opened out — which cooks faster and holds marinade.
• Shells into a bisque, a stock or a prawn oil. Roast them hard in oil, then strain. Free flavour that most people bin.
• Not simmered in a sauce for twenty minutes. This is the most common way they are wasted.

Common questions